A large set of inflammatory, degenerative, traumatic, infectious, autoimmune, orthopedic, vascular and neurological diseases are affecting the anatomy and physiology of the feet and the lower parts of the legs. The causes of these conditions and their treatments are very different. The foot diseases disturb in varying degrees the body. There are growing numbers of people during their professional activities (sportsmen, artists, military) that subject the lower extremities, including the feet, to high stress. On the other hand, there are multiple conditions and of high incidence affecting the lower limbs, such as diabetic foot ulcers (DFU), rheumatoid arthritis, deformities, inflammations and infections, circulatory, traumatic, and neuropathic conditions, among others. Methods of diagnosis of foot diseases and the lower parts of the legs are still insufficient.
The foot studies with images is a current scientific and clinical problem, with a growing number of works devoted to the subject [Suzuki E. Diabetologia (2000), 43: 165-172; Greenman R L., Diabetes Care (2005), 28: 6:1425-30; E. G Kavanagh, A. C Zoga, Seminars in Musculoskeletal Radiol (2006), 10: 4 308-27; Kapoor A, Arch Intern Med. (2007), 167:125-132; Johnson P. W, AJR (2009), 192: 96-100; Andreassen C. S., Diabetologia (2009), 52: 1182-1191; Moreno Casado M. J, Revista Intern. Ciencias Podológicas (2010), 4: 45-53; Poll L. W, Diabetology & Metabolic Syndrome (2010), 2: 2-5 (http://www.dmsjournal.com/content/2/1/25); Ramoutar C T, The J of Diabetic Foot Complications (2010), 2: 18-27; M. J. Sormaala, et al., Musculoskeletal disorders (2011), 12: 1-6; H. Kudo, et al. Jpn. J. Radiol (2012), 30: 852-857; W L. Sung, et al., The J. of Foot and Ankle Surgery (2012), 50: 570-574; Freud W., BMJ Open (2012), 2: 1-8]. In those cited works, the methods used are X-ray, Ultrasound, Computed Tomography, different modalities of nuclear medicine and MRI. Recent publications make comparative assessments of the aforementioned technologies to study the many foot conditions [B A Lipsky, et al. Clinical Infectious Diseases (2004), 39:885-910; Moholkar S, Appl. Radiology, www.appliedradiology.com, October (2009); Vartanians V. M, et al. Skeletal Radiol (2009), 38:633-636; Thomas-Ramoutar C, The J of Diabetic Foot Complications (2010), 2:18-27]. All imaging modalities are complementary. However, more and more articles give preference to the MRI for its non-invasiveness, sensitivity for the study of soft parts, its high spatial resolution and unmatched contrast, while providing anatomical and functional information [M. L. Mundwiler, et al. Arthritis Research and Therapy (2009), 11: 3, 1-10; Vartanians V. M, et al., Skeletal Radiol (2009), 38: 633-636; M. J. Sormaala, et al., Musculoskeletal disorders, (2011), 12: 1-6; H. Kudo, et al. Jpn. J. Radiol (2012), 30: 852-857; W L. Sung, et al., The J. of Foot and Ankle Surgery (2012), 50: 570-574].
However, in 2007, a published research describes a study of 602 patients with selective fat atrophy; they concluded that MRI diagnosis is uncertain [M. P. Recht, et al. AJR (2007), 189: W123-W127]. The cause of this conclusion is that patients were not studied under the same positioning conditions. The vast majority of MRI reports perform a qualitative assessment of the status of the foot, without giving continuity to the evolution (longitudinal studies), and those that do it, do not show guarantees of making it under equal conditions. Therefore, their conclusions are often cautious or are inconsistent with other work. For example, Edelman made a study of the clinical course of 63 DFU patients during six months [Edelman, D., J. Gen Intern Med (1997), 12: 537-543], concluding that the provision of MRI information is not determinant in differentiating osteomyelitis from other infectious conditions failing to predict the cure. In contrast, in another study [Kapoor A, Arch Intern Med. (2007), 167: 125-132], from a meta-analysis, data from different authors are discussed, comparing the sensitivity and specificity of MRI with conventional radiography and methods of technetium 99. At the same, it was demonstrated that MRI have higher specificity and sensitivity, for studies of osteomyelitis, than the other methods. Affirmations from the work published by Edelman in 1997 are inconsistent with works by other authors [Craig J C, Radiol. (1997), 203: 849-855; B A Lipsky, et al. Infections Clinical Infectious Diseases (2004), 39: 885-910; Collins M. S, AJR (2005), 185: 386-393; Kapoor A, Arch Intern Med. (2007), 167: 125-132; Tan, P L Teh J.; The British J. of Radiol (2007), 80: 939-948; Robinson A. H. N, J Bone Joint Surg [Br] (2009), 91-B: 1-7; Johnson P. W, AJR (2009), 192: 96-100]. In particular, in the work published by Craig the results of 15 MRI tests are correlated with the histopathology of 57 samples, proving prospectively that the diagnostic sensitivity was 90%, and the specificity was 71% [Craig J C, Radiol (1997), 203: 849-855]. Other authors declare different values for sensitivity and specificity, always above 50%, depending on the entities and comparison methods [Collins M. S, AJR (2005), 185: 386-393; Johnson P. W, AJR (2009), 192: 96-100; Thomas-Ramoutar C, The J of Diabetic Foot Complications (2010), 2: 18-27]. On the other hand, Freud W et al [Freud W., BMJ Open (2012), 2, 1-8] made a MRI study of the feet of 22 athletes, along a marathon race, at the beginning and during different stages of the race, to assess the effects caused by stress. In it, the size of the Achilles tendon and its distance to different lesions were measured. However, although the presence of edema is reported, the volume and the variation thereof were not measured. The reserved conclusions of this work do not have a rigorous quantitative foundation. The conformity between the different studies (of the feet and legs) together remains an unsolved problem. Quantitative and evolutionary evaluations of the different diseases that affect the feet are insufficient.
These discrepancies in the results, and the absence of reliable evolutionary quantitative studies, have some main reasons: the feet are structures of high biological variability between individuals, the feet have high mobility and their anatomical-functional characteristics are complex (they have 26 bones, 33 joints, 126 muscles and more than 100 tendons, vascular and nerve terminals with high mechanical load).
The patent application U.S. 2013/0053677 claims a device, a scanner, for studying foot lesions. In said patent document the plantar surface of the foot is scanned, and a three-dimensional reconstruction of the outer surface of the foot (foot skin) is done with software. This device and method do not allow the display, less the measurement of internal bone structures, muscles, ligaments, joints and their alterations. It applies only to some of the conditions of dermal nature in the plantar surface of feet. It does not solve the visualization, quantification and monitoring of the vast majority of diseases of the feet, as the DFU (appearing in any area of the feet, at different depths), rheumatoid arthritis, deformities, inflammations and infections, neuropathic and circulatory disorders, among others. This device is not connected to MRI studies. Moreover, only one foot is evaluated, which does not allow the comparison between them in the same conditions. Meanwhile, the patent application WO 2012/143628 A1 discloses a device and an orthopedic mechanic method for evaluating only partial damages of the anterior ligament of the knee.
The quantification of anatomical and physiological processes on the surface and inside of the foot, to provide new qualitative and quantitative information, and evolutionary information, virtually for all diseases of the lower extremities is not solved with these inventions.
In MRI foot studies the main problem is to obtain evolutionary and quantitative information of the several feet diseases, (including inflammatory processes that alter the sizes and relative locations of the anatomical structures) requiring that a fixed and reproducible position be achieved, along the different tests. To have quantitative information of existing pathophysiological processes in the feet and lower parts of the legs and their evolution, either spontaneously or as a result of treatments remains as an unsolved problem.